Thin Is in for Graphite Films

ELECTRONIC MATERIALS

Graphite films just a few atoms thick--and in some cases, as thin as a single atom--have been prepared as single, stable layers for the first time and incorporated into experimental devices [Science, 306, 666 (2004)].

A team led by physics professor Andre K. Geim and research associate Konstantin S. Novoselov at the University of Manchester, in England, managed to obtain the planar graphene sheets by repeatedly peeling layers off highly oriented pyrolytic graphite. They report that the process can yield superslim graphitic layers about 10 µm across, as well as larger ones that are about 3 nm thick and 100 µm in diameter.

Graphene films have been reported previously; these examples were either only a few nanometers in size or were chemically bound to a metal substrate, rather than in the free state. Until now, scientists had presumed that single graphene sheets would be too unstable to work with and that they would curve into more stable structures like soot or, under special conditions, nanotubes and fullerenes.

To study the films' physical properties, Geim and Novoselov's team used their thinnest films as field-effect transistors. They found that, even at room temperature, the materials were able to transport electrons at ultrafast speeds. No other film of similar thickness, they say, is known to behave in a comparable manner at ambient conditions.

"Graphene may be the best possible metal for metallic transistor applications," the researchers write. "However, by analogy to carbon nanotubes, other, nontransistor applications of this atomically thin material ultimately may prove to be the most exciting."